Many business enterprises use data-warehousing systems to store detailed business data for use in making tactical and strategic business decisions. An enterprise-wide data warehouse typically stores a wide variety of information from all areas of the enterprise's business activities, such as customer accounts, items purchased by customers, product sales and inventories at individual retail stores, product distribution, employee-personnel records, and financial records. Such an enterprise-wide data-warehousing system gives decision-makers a single, detailed view of the entire business and allows them to base decisions on information representing the business as it really is, not simply as they suspect it to be.
Because data-warehousing systems often serve many areas of an enterprise's business, the demands for data freshness in the data warehouse often vary. The customer-service department, for example, might require customer-account data that is current to within a few minutes, or even seconds, for use in scoring a customer to influence that customer's interaction with the enterprise. Having an up-to-the-minute view of the customer's interaction with the business enterprise better enables the enterprise's data-analysis tools to produce accurate results, taking into account the most recent interactions with the customer.
The enterprise's finance department, on the other hand, might need data that is updated only once per week or once per month. Departments such as this typically do not require, and in fact are often hampered by, the extreme levels of data freshness needed in other areas of the business enterprise. A department that generates performance analyses covering week-long or month-long periods typically does not want the data for those periods to change while the analyses are under way.
Enterprises have traditionally met demands for varying levels of data freshness by maintaining duplicate copies of data in multiple databases or tables. Some of these databases, such as those that serve customer service departments, are updated very frequently, e.g., every few minutes or seconds. The databases that serve other departments, such as finance departments, are refreshed less frequently, e.g., once per day, once per week, or even once per month, quarter, or year.